JPH1089523A - Electrically driven expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resist vibration and reduce cost by providing with a valve main body in which a fixed iron core having an inlet opening is fixed to one end of a pipe arranged a solenoid coil on an outer periphery and a stopper having an outlet opening is fixed to the other end, and control a flow rate while regulating a current-carrying rate of the solenoid coil. SOLUTION: In an electrically driven expansion valve adapted to a vehicular refrigeration circuit and the like, a movable iron core 22 abuts on a stopper 28 by a reset spring 23 at the time of non carrentcarrying. At this time, all narrow holes 24b of a nozzle 24 are opened by a piston 21, and throttle action of a refrigerant is carried out being brought into contact with a throttle hole 24a. When carrentcarrying of a solenoid 25 is carried out, tractive force is generated on the movable iron core 22, and the movable iron core 22 is moved to a position where tractive force of the movable iron core 22 caused by optimal current and drag of a reset spring 23 are balanced with each other. At this time, the piston 21 is also moved, and the narrow hole 24b of the nozzle 24 is closed according to its moving rate. Namely, an opening area of the narrow hole 24 to be closed is continuously changed, and a flow rate is obtained as necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve used for a refrigeration circuit using a refrigerant such as Freon, and more particularly to an electric expansion valve used for a vehicle such as an automobile.

[0002]

2. Description of the Related Art A typical example of an electric expansion valve used in a conventional refrigeration circuit will be described with reference to FIG. In the figure, reference numeral 1 denotes a valve body, and the valve body 1 is provided with a valve seat 2 in a flow path provided with a fluid inlet 1a and a fluid outlet 1b, and an externally threaded pipe 4 is fixed to the valve seat. The needle 3 is provided on the externally threaded pipe 4 so as to slide in the axial direction and to be able to contact and separate from the valve seat 2.

A rotor 6 having a female screw 7 at the center is rotatably screwed around the outer periphery of the male screw tube 4 and the needle 3 is held by the rotor 6 so as to be able to press through a spring 3a. I have. Further, a rotor case 9 is provided on the main body 1, and an electromagnetic coil 8 is arranged on the outer periphery of the rotor case 9.

A mandrel 11 around which a spiral guide ring 10 is wound is fixed axially inside the rotor case 9, and a slider 12 fixed to the rotor 9 is engaged with the guide ring 10. The rotor 6 is rotated more than necessary so that the needle 3 does not damage the valve seat 2. When the electromagnetic coil 8 is energized, the rotor 6 rotates to move the needle 3 toward and away from the valve seat 2.

[0005]

As can be seen from FIG. 3, the conventional electric expansion valve is an electric expansion valve using a stepping motor constituted by an electromagnetic coil 8 and a permanent magnet 5.
In order to stop the rotation of the rotor 6, a guide ring 10 and a slider 12 wound on a mandrel 11 are required, and the apparatus becomes complicated and large, and an expensive stepping motor must be used. It has a cantilever structure and is vulnerable to vibration.
Has a disadvantage that the operation response in the axial direction is deteriorated.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an inexpensive electric expansion valve that can control the amount of throttle of a refrigerant with a simple structure and is resistant to vibration.

[0007]

According to a first aspect of the present invention, there is provided a motor-operated expansion valve in which a fixed iron core having an inlet opening at one end of a pipe in which a solenoid coil is disposed on the outer periphery.
7 with an outlet opening 28a at the other end
And a communication hole 21 in the center axis direction.
a, and a piston 21 slidably disposed in the hole provided at the center of the fixed iron core 27 in the axial direction, and a return for returning the piston provided between the piston 21 and the fixed iron core 27. A spring 23, a movable iron core 22 having one end in contact with the piston 21 and having a communication hole 22a at the center and slidably provided in the tube 26; A plurality of small holes 24b having a hole 24a and being opened and closed by the piston 21 are provided on a side wall of a sliding portion with the piston 21. The nozzle 24 is fixed to the fixed iron core 27, and is connected to the solenoid coil 25. The inlet opening 27a of the fixed iron core is
The flow rate of the fluid flowing from the outlet to the outlet opening 28a of the stopper can be controlled.

[0008] In the electric expansion valve according to the second aspect,
The plurality of small holes 24b provided in the nozzle 24 can be opened and closed by the end of the piston 21, are displaced in an axial spiral, and the opening of each small hole 24b is partially It is characterized by being arranged to overlap. In the electric expansion valve according to the third aspect, the communication hole 21 a of the piston 21 and the communication hole 2
The opening area of 2a is set to be larger than the sum of the opening area of the throttle hole 24a provided in the nozzle 24 and the opening areas of the plurality of small holes 24b.

By adopting this configuration, the electric expansion valve of the first aspect is excellent in responsiveness because the solenoid 25 is used, and the movable iron core 22 is connected to the return spring 23 by increasing the current to the solenoid coil 25. The piston 21 moves to a position where the force and the traction force balance, and the piston 21 also moves to close the narrow hole 24b provided on the side surface of the nozzle 24, and finally stops by contacting the wall provided with the throttle hole 24a of the nozzle 24. .

Therefore, by adjusting the amount of current to the solenoid coil 25, the opening area of the narrow hole 24b on the outer periphery of the nozzle can be changed, and the flow rate of the fluid passing from the inlet opening 27a to the outlet opening 28a can be varied. Further, the piston 21 opens and closes the small hole 24b at the outer peripheral portion, so that the piston 21 does not receive a change in pressure from the inlet side due to the movement of the piston 21. The minimum flow rate for the opening area of the hole 24a is secured.

Further, the electric expansion valve according to the second aspect of the present invention includes the nozzle 2
4. When the openings of the plurality of small holes 24b provided in 4 are projected in a straight line, the openings are arranged so that a part of each opening overlaps, so that the opening area of the small holes 24b can be continuously changed according to the amount of movement of the piston 21. I have to.

Further, the electric expansion valve according to the third aspect is provided with communication holes 21a, 22a at the center of the piston 21 and the movable iron core 22.
Is set to be larger than the sum of the opening area of the throttle hole 24a provided in the nozzle 24 and the opening area of the plurality of small holes 24b, so that the pressure difference generated between the inlet opening 27a and the outlet opening 28a is reduced by the nozzle portion. Therefore, only the load of the return spring 23 acts on the movable iron core 22, so that a stable operation of the movable iron core 22 is obtained.

[0013]

1 is a view showing an embodiment of the present invention, in which (a) is a sectional view, (b) is an enlarged sectional perspective view of a nozzle, and (c) is a developed view of the nozzle. . The present embodiment includes a valve body 20, a piston 21, a movable iron core 22 having one end in contact with the piston, a return spring 23 for returning the movable iron core, and a nozzle for adjusting a flow rate in cooperation with the piston 21. 24. The valve body 20 has a fixed core 27 having an inlet opening 27a fixed to one end of a tube 26 having a solenoid coil 25 disposed on the outer periphery, and a stopper 28 having an outlet opening 28a at the other end.
Is fixed.

An inlet opening 27a is formed at one end of the fixed iron core 27, a nozzle 24 is fixedly provided at the center, and the other end is formed in a tapered shape. The fixed iron core 2
The nozzle 24 fixed at the center of the nozzle 7 has a cylindrical shape with a bottom. A throttle hole 24a is drilled at the bottom, and a plurality of fine holes 24b are drilled in the cylindrical portion in an axial spiral. The small holes 24b are arranged such that when they are projected in a straight line, the holes partially overlap each other. That is, as shown in the developed view of FIG. 3C, a part of each of the small holes 24b overlaps by Δ in the stroke direction of the piston. Therefore, when each of the small holes 24b is sequentially closed by the piston 21, the opening area does not become discontinuous.

One end of a piston 21 having a communication hole 21a in the center axis direction is slidably inserted into the cylinder of the nozzle 24. One end of the piston 21 The small hole 24b is opened and closed. A return spring 23 is inserted between the piston 21 and the fixed iron core 27.

The movable iron core 22 has one end connected to the piston 2.
1 and has a tapered surface at the same end as the fixed iron core 27 and a communication hole 22a in the center axis direction. Here, the communication hole 21a of the piston 21 and the communication hole 2 of the movable iron core 22 are formed.
The aperture area of the aperture hole 2a provided in the nozzle 24 is
And a plurality of small holes 24b are set to be larger than the total opening area.

The operation of the embodiment constructed as described above will be described with reference to FIG. FIG. 1 shows an example in which the present invention is applied to a refrigeration circuit for an automobile. A fixed iron core 2 is attached to a condenser 31 connected to an outlet of a compressor 30 driven by an engine.
7 is connected to form a high-pressure circuit section, and the outlet opening 28a of the stopper 28 is connected to the compressor 3
The low pressure circuit portion is formed by being connected to the evaporator 32 connected to the suction side of 0, the high pressure circuit portion and the low pressure circuit portion constitute a refrigeration circuit, and the refrigerant expands in the nozzle 24. I have.

When the solenoid coil 25 is not energized, the movable iron core 22 is pressed by the return spring 23, moves leftward, and contacts the stopper 28. In this state, the piston 21 opens all the small holes 24b of the nozzle 24, and performs the throttle action of the refrigerant together with the throttle hole 24a.

Next, when the solenoid coil 25 is energized, the movable iron core 22 facing the fixed iron core 27 on a tapered surface is
A traction force in the direction of the fixed core 27 proportional to the current can be obtained irrespective of the position in the axial direction.
To the position where the traction force of the return spring and the drag of the return spring are balanced. At this time, the piston 21 is pushed by the movable iron core 22 and closes the small hole 24b of the nozzle 24 at the end according to the amount of movement.

Therefore, by controlling the current to the solenoid coil 25, the narrow hole 24 closed by the piston 21 is controlled.
The opening area of b can be changed continuously, and a flow rate as required can be obtained. Further, the solenoid coil 25
When the amount of current flowing to the
To move the tip of the piston 21 to the throttle hole 2 of the nozzle 24.
Then, the flow comes into contact with the wall 4a and stops to secure the minimum flow rate corresponding to the throttle hole 24a.

The opening area of the communication hole 21a of the piston 21 and the communication hole 22a of the movable iron core 22 is set to be larger than the total opening area of the throttle hole 24a of the nozzle 24 and the plurality of small holes 24b, thereby restricting the refrigerant. Is received by the nozzle 24 and no external force is generated in the movable iron core 22 and the piston 21 by pressure, so that the movable iron core 22 and the piston 21 can stably operate with respect to the current to the solenoid coil 25.

[0022]

According to the electric expansion valve of the present invention, the use of a solenoid provides excellent responsiveness of the movable iron core and the piston of the movable part, and is resistant to vibrations because the return spring and the traction force of the solenoid are constantly applied. The structure that only the force of the return spring acts on the piston, the movable core, and the stable operation is obtained. By controlling the current to the solenoid coil, the optimal throttle that matches the engine speed and the temperature change of the evaporator This makes it possible to provide an electric expansion valve that is small in size, inexpensive, and excellent in responsiveness with a simple configuration using a solenoid.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, in which (a) is a sectional view, (b) is an enlarged sectional perspective view of a nozzle, and (c) is a developed view of the nozzle.

FIG. 2 is a diagram showing an example in which the embodiment of the present invention is applied to a refrigeration circuit for an automobile.

FIG. 3 is a sectional view showing an example of a conventional electric expansion valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Valve main body 21 ... Piston 22 ... Movable iron core 23 ... Return spring 24 ... Nozzle 25 ... Solenoid coil 26 ... Tube 27 ... Fixed iron core 28 ... Stopper 30 ... Compressor 31 ... Condenser 32 ... Evaporator

Claims (3)

[Claims] 1. A fixed core (27) having an inlet opening (27a) is fixed to one end of a tube (26) having a solenoid coil (25) disposed on the outer periphery, and an outlet opening (28a) at the other end.
Valve body (20) to which a stopper (28) having a lock is fixed
A piston (21) having a communication hole (21a) in the center axis direction and slidably disposed in the hole provided at the center of the fixed iron core (27) in the axial direction; and the piston (21). A return spring (23) provided between the piston and the fixed iron core (27) for returning the piston, one end of which is in contact with the piston (21);
A movable iron core (22) slidably provided in the tube (26) having a core (2a); a cylindrical shape with a bottom having a throttle hole (24a) in the bottom and a piston (21); A plurality of small holes (24b) that are opened and closed by the piston (21) are provided on the side wall of the sliding portion with the nozzle (2), and the nozzle (2) fixed to the fixed iron core (27) is provided.
4), wherein the flow rate of the fluid flowing from the inlet opening (27a) of the fixed iron core to the outlet opening (28a) of the stopper can be controlled by adjusting the amount of current supplied to the solenoid coil (25). And an electric expansion valve. 2. A plurality of small holes (24b) provided in said nozzle (24) are openable and closable by an end of a piston (21), are displaced in an axial spiral, and each of said small holes (24).
2. The motor-operated expansion valve according to claim 1, wherein the openings b) are arranged such that a part thereof overlaps each other when the openings are projected in a straight line. 3. A communication hole (21) of said piston (21).
a) and the opening area of the communication hole (22a) of the movable iron core (22) is the same as that of the throttle hole (24) provided in the nozzle (24).
2. The electric expansion valve according to claim 1, wherein the opening area is larger than the sum of the opening area of a) and the opening areas of the plurality of small holes.